2 Corinthians 1:19

He has appealed to the faithfulness of God, and this suggests the thought of the unchangeableness of Christ. ὁ τοῦ Θεοῦ γὰρ υἱὸς κ. τ. λ.: for the Son of God, Christ Jesus, who was proclaimed among you by us. The position of τοῦ Θεοῦ before γάρ (as in the true text) brings out the sequence of thought better, as it brings Θεοῦ (the connecting word) into prominence. διʼ ἐμοῦ καὶ Σιλουανοῦ καὶ Τιμοθέου : even by me and Silvanus and Timothy. These three brought the Gospel to Corinth (Acts 18:5), and were closely associated during the Apostle's labours in that city (1 Thessalonians 1:1; 2 Thessalonians 1:1). Silvanus is only another form of the name Silas; he was a prophet (Acts 15:32), and apparently, like St. Paul, a Roman citizen (Acts 16:37), and shared the Apostle's perils during the whole of his second missionary journey (Acts 15:40 to Acts 18:18). We hear of him again at Rome (1 Peter 5:12). οὐκ ἐγένετο ναὶ καὶ οὔ, ἀλλὰ ναὶ ἐν αυτῷ γέγονεν : was not Yea and Nay, but in Him is (sc., has been and continues to be) Yea. There is no doubtfulness or vacillation in the words of Christ (Matthew 7:29; John 12:50); and He continually emphasised the positive and certain character of His teaching by the introductory formula Ἀμὴν, ἀμήν. More than this, however, is involved here. Christ, who is the Object and Sum of St. Paul's preaching, is unchangeable (Hebrews 13:8), for He is not only “true” (Revelation 3:7), but “the Truth” (John 14:6): He is, in brief, ὁ Ἀμήν (Revelation 3:14), and so it may be said that an Eternal “Yea” has come into being (γέγονεν, through His incarnate Life) in Him.